The report describes the two conventions and their approaches and compares them with regard to control of mercury emissions from the coal combustion sector.
The UNFCCC is based on a top down approach, giving an overall goal for greenhouse gas reductions but with flexibility on how to achieve these reductions. The UNFCCC can be regarded as the instigator for activities and projects to reduce CO2 emissions from sources such as coal combustion. Even though many countries are still not parties to the convention, the activities underway are relatively aligned as many countries accept the potential environment consequences of elevated greenhouse gases and take similar approaches to reducing emissions. The solutions to reducing CO2 emissions from coal combustion appear somewhat simple – burn less coal, burn it more efficiently and apply CCS (carbon capture and storage). However, although the solutions may appear simple, in practice they pose significant challenges. Populations are growing and, with them, the demand for energy increases. Large populations are still waiting for electrification and to control emissions in the face of increased fuel use is not easy. Further, the CCS technologies which are vital to reducing emissions from existing and future plants are still far from commercialisation.
The Minamata Convention is new and in the early stages of implementation. However, many countries had already started to take action to reduce mercury emissions before negotiations had been completed. To date, approaches for mercury control have largely been on a source-specific basis and the majority of the legislation existing and impending are also source-specific approaches, for example the emission limit values in North America and some of Asia.
Although neither the UNFCCC nor the Minamata Convention call specifically for the phasing out of coal, they do set priorities which affect how coal is viewed by the public and how utilities must operate in the future. Both the conventions promote the more efficient use of coal where coal continues to be used.
The UNFCCC is primarily focussed on two options – the reduced or more efficient combustion of coal and the application of CCS, the latter being somewhat away from commercial deployment. The Minamata convention also may promote the reduced use of coal but also relies on currently available flue gas cleaning technologies and even changes in coal supply and demand (for cleaning, switching and blending options). Although Minamata does not directly list combustion efficiency as a requirement, this is certainly an approach that could be considered under BAT/BEP.
The flue-gas control technologies available for CO2 and mercury control are quite distinct. For the most part, any technology for one will not achieve a reduction in the other. However, detailed consideration must be given to ensure that a control technology for one pollutant does not result in increased emissions of the other. This means considering the final fate of mercury in any CCS system and also considering any negative plant efficiency resulting from the installation of mercury controls.
